二叉搜索树的后序遍历序列

题目描述

#include <iostream>

using namespace std;

bool VerifySquenceOfBST(int sequence[], int length)
{
	if(sequence == NULL && length <= 0)
		return false;
	
	int root = sequence[length -1];

	int i;
	for(i= 0; i < length-1; i++)
	{
		if(sequence[i] > root)
			break;
	}

	int j;
	for(j = i; j < length -1; j++ )
	{
		if(sequence[j] < root )
			return false;
	}

	bool left = true;
	if(i > 0)
	 left = VerifySquenceOfBST(sequence, i);

	bool right = true; //预定义为true，在最后如果为叶子节点的情况就出错了
	if(length - 1 - i > 0)
		 right = VerifySquenceOfBST(sequence, length - 1 - i);

	return (right & left);
	
}

// ====================测试代码====================
void Test(char* testName, int sequence[], int length, bool expected)
{
    if(testName != NULL)
        printf("%s begins: ", testName);

    if(VerifySquenceOfBST(sequence, length) == expected)
        printf("passed.\n");
    else
        printf("failed.\n");
}

//            10
//         /      \
//        6        14
//       /\        /\
//      4  8     12  16
void Test1()
{
    int data[] = {4, 8, 6, 12, 16, 14, 10};
    Test("Test1", data, sizeof(data)/sizeof(int), true);
}

//           5
//          / \
//         4   7
//            /
//           6
void Test2()
{
    int data[] = {4, 6, 7, 5};
    Test("Test2", data, sizeof(data)/sizeof(int), true);
}

//               5
//              /
//             4
//            /
//           3
//          /
//         2
//        /
//       1
void Test3()
{
    int data[] = {1, 2, 3, 4, 5};
    Test("Test3", data, sizeof(data)/sizeof(int), true);
}

// 1
//  \
//   2
//    \
//     3
//      \
//       4
//        \
//         5
void Test4()
{
    int data[] = {5, 4, 3, 2, 1};
    Test("Test4", data, sizeof(data)/sizeof(int), true);
}

// 树中只有1个结点
void Test5()
{
    int data[] = {5};
    Test("Test5", data, sizeof(data)/sizeof(int), true);
}

void Test6()
{
    int data[] = {7, 4, 6, 5};
    Test("Test6", data, sizeof(data)/sizeof(int), false);
}

void Test7()
{
    int data[] = {4, 6, 12, 8, 16, 14, 10};
    Test("Test7", data, sizeof(data)/sizeof(int), false);
}

void Test8()
{
    Test("Test8", NULL, 0, false);
}

int main(int argc, char* argv[])
{
    Test1();
    Test2();
    Test3();
    Test4();
    Test5();
    Test6();
    Test7();
    Test8();

    return 0;
}